Interruptable inking cylinder and scraper blade forming open ended fountain trough

ABSTRACT

Printing apparatus is constructed with an open-ended troughlike fountain defined by an anilox inking cylinder, a scraper blade, and a rigid support for the scraper blade. A plurality of fluidoperated power cylinders mounted directly to a common elongated manifold urge the scraper blade against the inking cylinder. A pan positioned below the fountain is shaped to catch ink flowing out of the fountain through the open ends thereof and direct such ink to the inlet of a pump which then directs the ink to a nozzle positioned above the fountain at a point midway between the ends thereof. The blade is constructed of a nonmetallic material to reduce wear of the anilox roll and improve uniformity of the ink film. Automatic means responsive to stopping of the printing cylinder moves the pressure cylinder away from the printing cylinder and also moves the entire troughlike fountain including the inking cylinder, away from the printing cylinder. An idler motor for the inking cylinder is connectable to drive all three cylinders for use in making proof prints.

United States Patent [72] lnventor Albert F. Shields 2,109,768 3/1938 Crabtree 101/351- Forest Hills, N.Y. 2,310,788 2/ 1 943 Hummelchen 101/350 21 Appl, No. 11,619 2,891,471 6/1959 Sengewald 101/350 [22] Filed Feb. 4, 1970 3,026,796 3/1962 Crawford 101/157 [45] Patented Dec. 28, 1971 3,060,853 10/1962 Remer.-.. 101/350 X [73] Assignee S 8: S Corrugated Paper Machinery Co., 3,196,787 7/1965 Finke 101/351 X Inc. 3,221,651 12/1965 Tagliasacchi 101/183 Brooklyn, N.Y. 3,288,061 11/1966 Doyce 101/366 X Continuation of application Ser. No.

This application Feb. 4, 1970, Ser. No. y 11,619

ABSTRACT: Printing apparatus is constructed with an openended troughlike fountain defined by an anilox inking [54] INTERRUP'IABLE INKING CYLINDER AND cylinder, a scraper blade, and a rigid support for the scraper SCRAPER BLADE FORMING OPEN ENDED bl de A l ralit f fluid-o erated owerc linders mounted FOUNTAIN rnouon P Y P y 10 claims 7Drawin Figs. d1rectly to a common elongated manifold urge the scraper 3 blade against the mkmg cylmder. A pan positioned below the [52] U.S.Cl 101/351, fountain is shaped to catch ink flowing out of the fountain 101/169, 101/366 through the open ends thereof and direct such ink to the inlet [51] lnt.Cl B4lf31/04, of a pump which then directs the ink to a nozzle positioned B41f31/36 above the fountain at a point midway between the ends [50] Field of Search 101/350, thereof. The blade is constructed ofa nonmetallic material to 351, 352, 363, 364, 365, 366, 207, 208, 209, 157, reduce wear of the anilox roll and improve uniformity of the 169 ink film. Automatic means responsive to stopping of the printing cylinder moves the pressure cylinder away from the printl References cited ing cylinder and also moves the entire troughlike fountain in- UNITED STATES PATENTS cluding the inking cylinder, away from the printing cylinder, 13647598 H1921 white et aL 101/352 An idler motor for the inking cylinder is connectable to drive 1,825,999 10 1931 Fankboner 101/365 8111111 finders use in making P100f P PATENTEDnmzanm Y 316130.146

SHEET 2 [1F 6 ICE-.5.

PATENTED UEC28 I97! SHEET 3 [IF 6 l' l I INVENTOR. AME/e7 A' 05105 PATENTED DEB28 lsm SHEET 5 OF 6 INTERRUPTABLE INKING CYLINDER AND SCRAPER BLADE FORMING OPEN ENDED FOUNTAIN TROUGH This application is a continuation of my copending application Ser. No. 693,899 filed Dec. 27, 1967, now abandoned, relating to printing apparatus in general and more particularly relating to novel printing apparatus having a troughlike ink fountain bounded by an inking cylinder and a scraper doctoring blade in contact with the inking cylinder.

Generally speaking, printing units for paperboard boxes are required to print individual sheets of material as distinguished from material in the format" a continuous web. This type of printing unit is often located adjacent to a device which slits, slots, and scores blanks and because of this dust particles and other foreign matter enter the fountain and interfere with the formation of the ink film on the inking cylinder.

In order to minimize the adverse effects of the condition noted above, printing units of this type are often provided with a so-called reverse angle or scraper blade doctoring means for the inking cylinder. Such a construction is illustrated in my US. Pat. No. 3,180,257 which issued Apr. 27, l965 for a Printing Unit, and is limited to a blade which is disposed at an acute angle to the tangent extending, from the blade line of contact with the inking cylinder, in the direction of rotation for the inking cylinder. This is in contrast to the more conventional so-called wiper-type doctoring blade which is disposed at an obtuse angle with respect to the aforesaid tangent. While a scraper blade is generally superior to a wiper blade for producing uniform film thickness on the inking cylinder, dust and other foreign particles complicate the job of a scraper blade doctoring means when the blade engages the inking cylinder along a line disposed above the level of ink in the fountain.

The instant invention obviates most of the difficulties of prior art constructions of this type by providing a troughlike fountain or pool formed between the inking cylinder, its scraper blade doctoring means, and a rigid adapter or support for the blade. A continuous inflow of ink to the fountain, at the center thereof and from above causes turbulent conditions in the fountain. This produces improved mixing of the ink so that a skin does not form on the ink in the pool and also causes dust and other foreign particles to rise to the ink surface and be driven away from the line of contact between the scraper blade and the inking cylinder, this line of contact being located near the bottom of the fountain.

Uniformity of ink thickness is improved by utilizing a nonmetallic scraper blade preferably constructed of plastic material comprising nylon with molybdenum disulfide and having a hardness in the range of 70-100 measured on commercially available durometers.

Uniformity of film thickness is further improved by utilizing a plurality of power cylinders mounted directly to a common manifold to bias the scraper blade against the outer surface of the inking cylinder. By mounting the power cylinders directly to the common manifold a large reserve of pressurized fluid is close at hand so that pressures in all cylinders are equalized almost instantaneously.

The rigid elongated member or adapter which holds the scraper blade is removably mounted to a pivoted support. The power cylinders act upon the blade support and since the latter is rigid, most of the force exerted by these power cylinders is used to bias the scraper blade against the inking cylinder rather than to straighten the blade. Thus, a lower total force may be utilized.

w The utilization of a readily mounted and dismounted blade holder reduces downtime of the printing apparatus since by having a spare blade holder a new blade may be mounted in operative position to the second blade holder while the latter is on the bench rather than while the blade holder is in a machine that is stopped.

Automatic means are provided so that upon stopping of the printing cylinder the inking and pressure cylinders automatically move away from the printing cylinder. The scraper blade and inking cylinder are mounted to a common support so that even when the inking cylinder moves away from the printing cylinder the relationship between the inking cylinder and scraper blade is not disturbed. Thus, the ink film remains uniform and is at desired thickness when printing is resumed.

Apparatus of the instant invention is also provided with a clutch means selectively operable to enable the inking cylinder idler motor to drive all three cylinders when the main drive motor is not driving the apparatus so that proof prints may be obtained.

Accordingly a primary object of the instant invention is to provide a novel construction for printing apparatus usable in a relatively dusty environment.

Another object is to provide printing equipment having novel means for obtaining uniform ink film thickness.

Still another object is to provide printing apparatus utilizing a nonmetallic scraper blade doctor means in conjunction with an etched inking cylinder with these elements providing boundaries for a troughlike ink fountain.

A further object of this invention is to provide novel printing apparatus having a troughlike inking fountain open at both ends with ink being fed continuously to the fountain at a point intermediate the ends thereof.

A still further object is to provide novel printing apparatus including means for automatically moving the pressure cylinder and inking cylinder away from the printing cylinder when operation of the latter ceases and also including a mounting for the doctoring means so constructed that adjustment between the doctoring means and inking cylinder is not disturbed upon movement of the latter away from printing cylinder.

Yet another object is to provide printing apparatus in which the idler motor, that drives the inking cylinder when printing is not taking place, may be used to drive the printing apparatus for obtaining proofs.

These as well as other objects of this invention will become readily apparent after reading the following description of the accompanying drawings in which:

FIG. 1 is a side elevation in schematic form illustrating a fragmentary portion of box-making apparatus including two printing units constructed in accordance with the teachings of the instant invention.

FIG. 2 is a perspective of one of the printing units of FIG. I looking at the unit from the rear thereof.

FIG. 3 is a side elevation looking in the direction of arrows 3-3 of FIG. 2 showing the driving elements for the printing unit.

FIG. 4 is a side elevation of the inking and printing elements looking in the direction of arrows 4-4 of FIG. 2.

FIG. 5 is an enlarged portion of FIG. 4 showing the printing unit in region of the inking fountain. v

FIG. 6 is a plan view of the inking cylinder and doctoring means looking in direction of arrows 6-6 of FIG. 4.

FIG. 7 is a developmental view showing the relationship between the linkages for operating the inking cylinder into and out of engagement with the printing cylinder, and the doctoring means. In FIG. 7 the linkages are shown in side elevation while the doctoring means is shown in plan view.

Now referring to the figures. In FIG. 1 two printing units, 20,20 are positioned in tandem in front of sheet-feeding means 21 and behind creaser-slotter 22 which receives printed blanks from printing units 20,20 and transfers them to rotary diecutter 23 positioned forward of creaser-slotter 22. Foldergluer 24 positioned forward of diecutter, 23, receives printed but unfolded box blanks issuing from diecutter 23, applies glue to glue flaps of these blanks and thereafter transforms the blanks into folded tubular boxes. Main drive motor 30, located adjacent to folder-gluer 24, provides power for coordinated operation of units 20,20 21,22 and 23.

As seen most clearly in FIGS. 2 through 5, printing unit 20 includes impression or pressure cylinder 26, inking cylinder 27, printing cylinder 25 positioned between cylinders 26,27 and inking-doctoring means 28 positioned at the rear of inking cylinder 27.

As best seen in FIG. 5 inking-doctoring means 28 includes scraper blade 31 having its upper horizontal edge in engagement with the periphery of inking cylinder 27 being urged thereagainst by fluid pressure means 32 acting through rigid support 33 and rigid adapter or blade holder 34. Screws 35 and clamping member 36 securely mount blade 31 to holder 34. Dovetail formation 37 mounts holder 34 along its lower edge to support 33 while screws 38 and clamping member 39 engage the upper edge of holder 34 and securely mount this edge against support 33.

Pressure means 32 comprises elongated manifold 41 having fluid-operated power cylinders 42 mounted directly thereto and equally spaced along the length of manifold 41. Operating extension 43 of each cylinder 42 projects forward of manifold 41 engaging the rear surface of support 33 urging the latter in a counterclockwise direction about pivot 44.

Doctoring means 28 is pivotally mounted to carriers 47 by pins 45 extending outwardly from end plates 46 of manifold 41 and received by apertures of carriers 47. Studs 48, pivotally connected to carriers 47, and extending through slots open at one end in brackets 51 secured to manifold 41, threadably receive nuts 49 provided for adjusting the angle at which blade 31 engages inking cylinder 27. Setscrew 99 (FIG. 7) fastened in plate 47 engages bracket 51 in such a manner as to limit inward motion of manifold 41 thereby positively locating the latter. Nuts 49 secure doctoring means 28 in its operative position shown in FIGS. 2 through 5 and also pennit doctoring means 28 to readily be released and to pivoted, by utilizing handle 52, to a position wherein blade holder 34 is accessible for dismounting from mounting member 33.

Carriers 47,47 are pivotally mounted to portions of individual hollow stationary horizontally spaced vertical frame sections 50,50 by being secured directly to sleevelike supports 53 which are pivotally mounted in circular cutouts 54 of stationary frame sections 50. Each cutout 54 is formed about center 56 which is offset forward of the longitudinal or rotational axis 55 of inking cylinder 27 for a reason to be hereinafter explained. Cam roller 47A, pivotally mounted to nose 47B projecting forwardly of carrier 47, is engageable with stop 58 to limit clockwise movement (with respect to FIG. 5) of carrier 47 thereby limiting upward movement of inking cylinder 27 toward printing cylinder 25. The position of stop 58 is adjustable by means of worm 59 which drives gear 60 keyed to shaft 61, with the latter threadably mounting sleeve 62 having stop 58 at its upper end. The position of stop 58 sets the contact or kiss between inking cylinder 27 and printing cylinder 25.

Ink fountain or pool 65 is formed at the nip between printing cylinder 27 and scraper blade 31 with blade holder 34 forming another boundary for fountain 65. Fountain 65 extends for the entire length of inking cylinder 27 and is open ended so as to permit ink to flow out both ends thereof. Curved deflectors 64, secured at each end support 33, direct ink flowing out of fountain 65 downward into pan 66. The bottom of pan 66 is sloped so as to direct ink to a reservoir by means of gravity. Ink is drawn from the reservoir by a pump which delivers this ink through conduit 68 to outlet noule 69 positioned above fountain 65 at a point substantially midway between the ends of inking cylinder 27. In the alternative ink flowing from pan 66 may go directly to a pump which moves the ink to a raised reservoir from which the ink flows through conduit 68 and nozzle 69 by means of gravity. When printing unit is operating there is a continuous flow of ink from nozzle 69 into fountain 65 to cause continuous circulation of ink in pool 65 with ink flowing into pool 65 at such a rate that the line of engagement 70 between scraper blade 31 and inking cylinder 27 is always below the upper surface of the ink pool in 65.

Since doctoring means 28 and inking cylinder 27 are both mounted directly to carriers 47, when carriers 47 are pivoted on frame 50 to move inking cylinder 27 relative to printing cylinder the relationship between doctor blade 31 and inking cylinder 27 remains unchanged. Thus, when inking cylinder 27 is moved away from printing cylinder 25 during periods when sheets are not being fed through printing unit 20, the ink film thickness on inking cylinder 27 remains proper so that immediately upon reengagement of inking cylinder 27 with printing cylinder 25, the proper amount of ink will be transferred to the latter without the necessity of readjusting doctoring means 28.

It is noted that the outer surface of inking cylinder 27 is etched to constitute what is known as an anilox roll. It is also noted that scraper blade 31 is preferably constructed of nonmetallic material such as hard rubber or a compound of nylon with molybdenum disulflde. Blade materials of 70 to I00 durometers have produced desirable operating results. In any event the material of blade 3l should not be so soft as to readily deflect and permit streaking due to hydrodynamic effects when inking cylinder 27 is rotated at relatively high speeds, and the material of blade 31 should not be so hard as to cause excessively rapid wear of inking cylinder 27.

Main drive motor 30, acting through conventional gearing and a common drive shaft (shown as centerline 98 in FIG. 1) connects folder-gluer 24, diecutter 23', and creaser-slotter 22 for coordinated operation. Gear 71 in the creaser-slotter section 22, driven in a clockwise direction with respect to FIGS. 1 and 3, meshes with gear 72 of the rightmost printing unit 20 which in turn meshes with gears 73 and 74, the latter being a duplicate of gear 71. Gear 73 drives gear 75 while gear 74 drives gears 76 and 77. Gears 71-77 are driven in the directions of the respective arrows thereon. Gear 74 of the right printing unit 20 drives gear 72 of the left printing unit 20, and gear 74 of left printing unit 20 drives sheet feeder 21.

Gear 74 is directly keyed to printing cylinder 25, gear 76 is connected through an oldham coupling to drive impression cylinder 26, and gear 77 is connected through another oldham coupling and air operated clutch 78 (FIG. 6) to drive inking cylinder 27. Gear 73 is keyed for direct drive of a lower delivery roll (not shown) while gear 75 acting through another oldham coupling drives upper delivery roll (not shown). As is well known to the art, the provisions of oldham couplings permits shafts driven therethrough to be moved perpendicular to their rotational axes relative to their respective drive centers.

When gear 77 is disengaged from gear 74 idler motor 29 acting through overrunning clutch 79 (FIG. 6) continues to drive inking cylinder 27 thereby preventing ink from hardening on inking cylinder 27. While idler motor 29 has sufficient power to drive all of the elements of one printing unit 20, motor 29 does not have any substantial additional power. Therefore, in order to run proofs using only power from idler motor 29, printing unit 20 must be disengaged from the other units shown in FIG. 1. Thus, each unit 20 is provided with wheels 81 riding on rails 82 extending parallel to the direction of paper feed indicated by arrow A in FIG. 4. Similar wheels are provided for sheet feeder 21 so that this unit can be moved along rails 82. A power-operated pinion means (not shown) in feed unit 21 in engagement with a stationary rack (not shown) parallel to rails 82 is provided for moving units 21, 20, 20 along rails 82 when they are locked together by releasable mechanical connecting means. With printing unit 20 mechanically disengaged from adjacent units, and with clutch 78 engaged, idler motor 29 is effective to rotate all of the printing unit cylinders and the delivery rolls.

When operation of printing unit 20 ceases, that is, when printing cylinder 25 stops rotating, both pressure cylinder 26 and inking cylinder 27 must be moved away from printing cylinder 25. These operations, together with deactivation of clutch 78 are accomplished automatically when ever the main drive motor 30 is deactivated. In this connection it is noted that impression cylinder 26 is mounted to frame members 50,50 on carriers that are pivoted eccentrically with respect to the rotational axis of cylinder 26. Double acting power cylinder 97 (FIG. 1) is crank connected to these carriers through shaft 96 and pinions (FIG. 3) for operating the latter to raise cylinder 26, moving it upward and away from printing cylinder25 automatically when main drive motor 30 is deactivated.

Similarly, when main drive motor 30 is deactivated, doubleacting power cylinders 85,85 mounted adjacent to each vertical frame section 50,50, act through linkages to pivot carriers 47,47 in a direction to lower inking cylinder 27 and doctoring means 28. Each of these linkages includes clevis 86 connected to movable piston extension 87 of power cylinder 85, rods 88a and 88b connected by pins 91,91 and bolt 92 (FIG. 7) with the upper end of rod 880 being pivotally connected to clevis 86 and the lower end of rod 88b being formed as a clevis pivotally connected at pin 90b to carrier 47. Thus, when main drive motor 30 is stopped, power cylinder 85 is automatically actuated to lower rods 88a, 88b and in so doing carrier 47 is pivoted counterclockwise from its position shown in FIG. 5 thereby moving the rotational axis 55 of inking cylinder 27 counterclockwise with respect to the pivotal axis 56 of carrier 47 to move inking cylinder 27 out of engagement with printing cylinder 25.

Thus, it is seen that the instant invention provides a novel construction for a printing unit which is to be operated in a dusty or otherwise dirty environment. In particular, this printing unit includes a nonmetallic scraper blade for doctoring an etched inking cylinder and cooperating therewith to form'a troughlike fountain that is continuously supplied with ink that entersat the center and above the fountain and flows out the ends thereof.

The embodiments of the invention in which an exclusive privilege or property is claimed are defined as follows:

1. Printing apparatus comprising a printing cylinder; a pressure cylinder disposed to urge sheet material passing between said cylinders into operative engagement with said printing cylinder; an inking cylinder in operative engagement with said printing cylinder for transferring ink thereto; means mounting said cylinders for rotation about their longitudinal axes with said axes positioned substantially parallel and horizontal; blade means extending parallel to said axes and having an edge thereof in engagement with said inking cylinder along a line parallel to said axes; said blade means being disposed at an acute angle to the tangent extending from said line in the direction of rotation for said inking cylinder; a support means to which said blade means is mounted; said blade means, said support means, and said inking cylinder cooperating to form a troughlike fountain having end openings through which ink flows out of said fountain to maintain ink circulation therein; first means for supplying ink to said fountain to a level above said line; an common movable mounting means to which both said inking cylinder and said support means are mounted, whereby said blade means and said inking cylinder move in unison so that the operative relationship between said blade means and said inking cylinder remains unchanged as said mounting means is operated to move said inking cylinder toward and away from said printing cylinder.

2. Printing apparatus as set forth in claim 1 in which said first means comprises pump means and an outlet nozzle positioned above said fountain; second means constructed to direct ink to said pump means which in turn moves this ink toward said nozzle; said nozzle being positioned to supply ink to said fountain at a single region located intermediate the ends of said fountain.

3. Printing apparatus as set forth in claim I, in which there is a second means positioned to catch ink flowing out of said fountain through the end openings thereof; said second means including a pan having a bottom interior surface shaped and positioned to direct ink flow by means of gravity to an outlet of said pan.

4. Printing apparatus as set forth in claim 1, in which said support is elongated and rigid; fluid pressure means acting at longitudinally spaced locations along said support to urge said edge of said blade means against said inking cylinder.

5. Printing apparatus as set forth in claim 4, in which said fluid pressure means comprises an elongated manifold, a plurality of power cylinders mounted directly to said manifold, and a plurality of pistons each mounted in an individual one of said power cylinders for limited movement transverse to the length of said manifold.

.Prmting apparatus as set forth in claim 1 in which said blade means is constructed of a strip of nonmetallic material; said nonmetallic material being a compound whose main constituent is nylon.

7. Printing apparatus as set forth in claim 1, also comprising means for connecting said cylinders to a main source of driving power to rotate said cylinders at adjustable normal operational speeds; an idler motor for rotating said inking cylinder when the main source of power is operatively disconnected from said cylinders; clutch means for selectively connecting and disconnecting said pressure and said printing cylinders to said idler motor whereby said idler motor may be used to drive all of said cylinders to obtain proof prints when said main source of power is operatively disconnected from said cylinders.

8. Printing apparatus as set forth in claim 7 in which said inking cylinder is provided with an outer surface that is etched.

9. Printing apparatus as set forth in claim 1, also comprising means connected to said mounting means and said pressure cylinder to automatically move said inking and said pressure cylinders away from said printing cylinder when rotation of said printing cylinder is stopped.

10. Printing apparatus as set forth in claim 1, in which said support means includes a blade holder, a support, securing means and clamping means securing said blade means directly to said holder; said securing means removably mounting said holder and said blade means, as a unit, to said support. 

1. Printing apparatus comprising a printing cylinder; a pressure cylinder disposed to urge sheet material passing between said cylinders into operative engagement with said printing cylinder; an inking cylinder in operative engagement with said printing cylinder for transferring ink thereto; means mounting said cylinders for rotation about their longitudinal axes with said axes positioned substantially parallel and horizontal; blade means extending parallel to said axes and having an edge thereof in engagement with said inking cylinder along a line parallel to said axes; said blade means being disposed at an acute angle to the tangent extending from said line in the direction of rotation for said inking cylinder; a support means to which said blade means is mounted; said blade means, said support means, and said inking cylinder cooperating to form a troughlike fountain having end openings through which ink flows out of said fountain to maintain ink circulation therein; first means for supplying ink to said fountain to a level above said line; an common movable mounting means to which both said inking cylinder and said support means are mounted, whereby said blade means and said inking cylinder move in unison so that the operative relationship between said blade means and said inking cylinder remains unchanged as said mounting means is operated to move said inking cylinder toward and away from said printing cylinder.
 2. Printing apparatus as set forth in claim 1 in which said first means comprises pump means and an outlet nozzle positioned above said fountain; second means constructed to direct ink to said pump means which in turn moves this ink toward said nozzle; said nozzle being positioned to supply ink to said fountain at a single region located intermediate the ends of said fountain.
 3. Printing apparatus as set forth in claim 1, in which there is a second means positioned to catch ink flowing out of said fountain through the end openings thereof; said second means including a pan having a bottom interior surface shaped and positioned to direct ink flow by means of gravity to an outlet of said pan.
 4. Printing apparatus as set forth in claim 1, in which said support is elongated and rigid; fluid pressure means acting at longitudinally spaced locations along said support to urge said edge of said blade means against said inking cylinder.
 5. Printing apparatus as set forth in claim 4, in which said fluid pressure means comprises an elongated manifold, a plurality of power cylinders mounted directly to said manifold, and a plurality of pistons each mounted in an individual one of said power cylinders for limited movement transverse to the length of said manifold.
 6. Printing apparatus as set forth in claim 1 in which said blade means is constructed of a strip of nonmetallic material; said nonmetallic material being a compound whose main constituent is nylon.
 7. Printing apparatus as set forth in claim 1, also comprising means for connecting said cylinders to a main source of driving power to rotate said cylinders at adjustable normal operational speeds; an idler motor for rotating said inking cylinder when the main source of power is operatively disconnected from said cylinders; clutch means for selectively connecting and disconnecting said pressure and said printing cylinders to said idler motor whereby said idler motor may be used to drive all of said cylinders to obtain proof prints when said main source of power is operatively disconnected from said cylinders.
 8. Printing apparatus as set forth in claim 7 in which said inking cylinder is provided with an outer surface that is etched.
 9. Printing apparatus as set forth in claim 1, also comprising means connected to said mounting means and said pressure cylinder to automatically move said inking and said pressure cylinders away from said printing cylinder when rotation of said printing cylinder is stopped.
 10. Printing apparatus as set forth in claim 1, in which said support means includes a blade holder, a support, securing means and clamping means securing said blade means directly to said holder; said securing means removably mounting said holder and said blade means, as a unit, to said support. 